Methods for producing a sugar crystal-containing liquid generally comprise steps of preparing a liquid supersaturated with sugar, adding seed crystals to the liquid, and stirring them.
By the stirring, a shearing force is applied on the liquid to crystallize sugar. To promote the crystallization of sugar, a high stirring speed may be employed. However, when a too much high stirring speed is employed, a liquid temperature rises so that it is difficult to maintain an adequate degree of supersaturation in some cases. Besides, the rise of a liquid temperature may cause the sugar crystals to dissolve.
The seed crystals promote the crystallization of the sugar. A size, shape or amount of the seed crystals to be added affects a size, shape or the number of grains in graining. Therefore, setting of the size, shape and amount of the seed crystals to be added are important in the method for crystallizing the sugar. For Example, when the amount is too small, a sufficient amount or number of sugar crystals are not obtained in some cases.
The following Patent Literature 1 discloses “A method for producing a slurry comprising microcrystals of a saccharide or sugar alcohol, wherein the method comprises steps of producing a sugar liquid by dissolving a saccharide or sugar alcohol, which his less soluble in water at a low temperature, in high-temperature water in a high concentration; cooling the sugar liquid to a supersaturation temperature; rapidly stirring the sugar liquid; and making the sugar liquid into a laminar flow state in a predetermined time during which complete crystallization does not occur, to allow the sugar in the sugar liquid to crystallize as microcrystals” (Claim 1).
The following Patent Literature 2 discloses “A continuous crystallization method of anhydrous crystalline fructose, wherein the method comprises steps of continuously supplying a fructose solution having a fructose content of 90% or more and a solid content of 87 w/w % or more, and a crystal-containing solution of a large amount, that is, 0.5 to 5 parts relative to 1 part of the fructose solution, to a graining tower having a rapid stirrer, and rapidly mixing them at 40 degrees C. to 50 degrees C.; and continuously supplying the obtained solution mixture to a crystallization tower, and gradually cooling the solution mixture under conditions where new crystals do not spontaneously arise, so as to grow crystals” (Claim 1).
The following Patent Literature 3 discloses “A method for producing whey powder, wherein the method comprises steps of homogenizing milk sugar crystallized in advance in a whey condensed liquid by a homogenizer to crush milk sugar crystals to a size of 100 mesh or less; and then performing pressure spray drying using a nozzle atomizer” (Claim 1). The Patent Literature 3 further discloses that “when the milk sugar is crystallized in the whey condensed liquid in advance, the condensed liquid is rapidly cooled to produce microcrystals of the milk sugar” in the method of claim 1 (Claim 2).
The following Patent Literature 4 discloses “A method for producing an isomaltulose-containing solid from a sugar liquid by making an enzyme producing isomaltulose from sucrose act on a sucrose liquid to produce an isomaltulose-containing sugar liquid, wherein the method comprises steps of crystallizing isomaltulose with a median diameter of 5 to 60 μm in the sugar liquid wherein the median diameter is measured by laser diffraction particle size distribution measurement; and spray-drying the sugar liquid comprising the isomaltulose crystals at a hot air temperature of 50 to 95 degrees C.” (Claim 1). The afore-mentioned crystallization of isomaltulose is carried out by adjusting a Brix of the isomaltulose-containing sugar liquid and then aging the sugar liquid (paragraph 0033).